Abstract
The European Advisory Board on Cat Diseases (ABCD) has published the first European prevention and treatment guidelines for feline calicivirus (FCV) infection.
FCV is a very common viral cause of feline oral and upper respiratory disease (‘cat flu’), and often occurs in combination with other pathogens, such as feline herpesvirus (FHV-1).
‘Like most RNA viruses, FCV is a highly variable virus and constantly mutates. Numerous strains of feline calicivirus exist - and more may come up every day,’ explained Dr Alan Radford (Liverpool University), ABCD member and internationally recognised specialist on feline calicivirus. ‘This is also why we see a variation in virulence, antigenicity and post-infection immunity. Cats that have recovered from an FCV-associated disease probably do not have lifelong protection against further episodes of disease, particularly if caused by different strains,’ Dr Radford said.
ABCD recommends that boosters should be given at three-yearly intervals for cats in low-risk situations (eg, indooronly cats with no contact with other cats). However, cats living in crowded, high-risk conditions like shelters should be re-vaccinated every year. For all other cats an informed decision should be made on the basis of a risk-benefit analysis.
‘The ABCD appreciates that single-component FCV vaccines are unavailable and that those currently on the market are combinations with feline herpesvirus-1 and other elements,’ explained Professor Marian Horzinek (Utrecht, The Netherlands), ABCD chairman. ‘An annual booster to protect against FCV disease may therefore entail the injection of other antigens that may induce longer-lasting protection’.
In view of the FCV variability, several vaccine strains have been developed over the years. In the absence of compelling published data, it is currently difficult to make a general recommendation about which vaccine to use. However, if FCV-related disease occurs in fully vaccinated cats housed in groups, changing to a different vaccine antigen may improve the clinical situation.
Typically, acute FCV infections cause oral ulcers, upper respiratory symptoms and a high fever. FCV can also cause transient arthritis. Furthermore, FCV is found in nearly all cats with chronic stomatitis or gingivitis. Although these signs might be due to an immune-mediated reaction, the exact role of FCV remains unclear.
Finally, incidents of a more severe, systemic form of FCV infection have been observed recently, both in the USA and Europe, mainly affecting adult cats and causing severe systemic signs. Currently available vaccines appear to provide limited protection against this particular, often fatal, form of FCV. Fortunately, this form of the disease is currently rare.
FCV is mainly transmitted through direct contact with saliva, ocular and nasal discharges of infected cats. They may shed the virus for several weeks or even months, well after the clinical signs have disappeared. FCV infection is very common, especially wherever cats are kept in groups. Kittens in particular are very susceptible to the virus.
ABCD recommends that all healthy cats and kittens should be vaccinated against FCV for optimal protection. Kittens should receive a primary vaccination course, with the second dose given not before the age of twelve weeks.
‘In high-risk situations, such as shelters, boarding catteries and cat colonies, it may be advisable to give kittens a third dose at 16 weeks, as maternal antibodies against FCV may persist beyond twelve weeks,’ added Dr Radford.
This applies particularly to situations where FCV has been shown to cause disease in vaccinated kittens in the past. For further details and downloads of the full-text ABCD Feline Calicivirus Disease Guidelines, visit www.abcdvets.org. These guidelines also give recommendations for specific situations, such as immunocompromised cats, breeding catteries and cats undergoing corticosteroid treatment.